Computing and Interpreting Return on Assets and Its Components McDonald’s Corporation (MCD) reported the following balance sheet and income statement data for 2013 through 2015.

$ millions Total Assets Net Income Sales 2013 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $36,626.3 — —

2014 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34,227.4 $4,757.8 $18,169.3 2015 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37,938.7 4,529.3 16,488.3 Required

a. What is MCD’s return on assets for 2014 and 2015? Disaggregate MCD’s ROA into its net profit margin and its asset turnover.

b. What factor is mainly responsible for the change in MCD’s ROA over this period?